The ability to selectively open ports along a tubular has applications in various industries. For example, in industries involving boreholes into earth formations, tubulars positioned within the borehole may have ports therealong that are originally closed but are desired to be opened individually and selectively. Systems have been developed that allow an operator to pump a ball to a ball seat sized to sealably engage the ball. Once engaged, pressure can be applied to move the ball seat and a sleeve attached thereto until the sleeve uncovers a previously covered port through the tubular. Such systems, however, have inherent dimensional restrictions due to the variously sized ball seats needed to engage the variously sized balls. Additionally, these systems can only open the ports in an ever upstream moving sequence due the fact that larger balls cannot pass through a smaller dimensioned seat. Systems that overcome the foregoing drawbacks are desirable in the art.